The exemplary embodiments described herein relate to systems and methods for analyzing cement additives.
Set cement compositions are used in the oil and gas sector for many purposes including stabilizing wellbores and plugging wellbores. Set cements are produced from cement slurries that include hydraulic cements in water with other cement additives. The operational parameters relating to the cement slurry and the properties of the resultant set cement are derived, at least in part, from the composition and concentration of the cement additives. For example, set retarders and set accelerators are used to establish a set time for the cement slurry that provides sufficient time to place the cement slurry in a predetermined location without having to wait too long for the cement to set once placed. In other examples, fillers may be used to achieve desired mechanical properties in the set cement (e.g., ground marble to increase the compressive strength and rubber to increase yield strength). Additionally, fillers like gas may be used to increase the permeability of the set cement.
Cement slurry formulations are developed to take into account the effects of each of the cement additives to yield the desired cement slurry operational parameters and set cement properties. Variations in the quality or quantity of any of the cement additives may affect the cement slurry operational parameters and set cement properties. For example, increased salt concentration from the water supply or another cement additive may accelerate or retard the set time of the cement slurry depending on concentration. Increasing the set time increases the cost of the cementing operation because of the nonproductive time associated with waiting for the cement slurry to set. In another example, magnesium salts like magnesium chloride, which can be a contaminant in silica fillers and some water supplies, expand after the cement slurry has set causing cracks and leaks in the set cement. Costly remedial operations may then need to be performed to plug the cracks.
Generally, the composition of cement additives is analyzed after production. However, the composition of the cement additives may change over time, for example, due to storage time, shipping conditions, storage conditions at the manufacture or at the well site, and the like. Compositional changes that may arise then allow for producing cement slurries that are not in spec with the developed cement slurry formulation, which as described above may have costly and time consuming results.